1. Field of the Invention
The present invention relates to a color mixing detection method, a color mixing detection apparatus, and a printing apparatus for detecting the color mixing of ink caused in an inkjet printing head.
2. Description of the Related Art
Inkjet printing heads (hereinafter referred to as printing heads) provided in an inkjet printing apparatus include those capable of ejecting a plurality of colors of inks through different ejection ports. Generally, a manufacture step of such a printing head includes an inspection step to detect a color mixing in which a different color of ink is mixed in the printing head. Specifically, ink is ejected from a manufactured printing head to print an evaluation pattern on a printing medium. Then, based on the color shade of the printed pattern, the occurrence of the color mixing in the printing head is detected.
Japanese Patent Laid-Open No. H10-151753(1998) discloses a method of detecting a change of a color shade of a printed image due to the color mixing in ink for example. Specifically, an image is printed on a printing medium by key color inks. Then, the result of reading the image is compared with a stored acceptable range of the color shades of the key colors to thereby determine whether the printed image has a correct color shade or not.
According to the detection method disclosed in Japanese Patent Laid-Open No. H10-151753(1998), the occurrence of the color mixing is detected only based on the change of the color shade of the printed image. Thus, if the color shade changes due to foreign matters (e.g., dust) existing on the printing medium, it is difficult to detect the occurrence of the color mixing with a high accuracy.